Bring a large pot of water to a boil. Add broccoli and cook, uncovered, until just tender -- about 6 minutes. Drain well. Transfer to a serving bowl.

In a small saucepan, melt butter over medium heat until it starts to brown. Immediately add chopped rosemary and 1 tsp salt, swirling to blend. Pour hot butter mixture over broccoli. Season with pepper. Toss to combine. Serve hot.